1. Field of the Invention
The present invention relates generally to valves, and in particular to industrial check and block valves.
2. Description of the Related Art
In industrial operations with piping systems, such as hydrocarbon refineries, petrochemical plants, and onshore or offshore hydrocarbon production projects, a standardized piping system can have a set face to face dimension provided for each valve that restricts the valve space within the piping system to assure standardization and interchangeability with any type of valve from different manufacturers for a given pressure system. This spacing standardization is applicable to both block valves, which can open and close to turn a fluid flow on and off, and check valves, which are non-return flow valves.
In such application, the piping systems are often provided with flanges for attachment to the valves. Therefore the spacing allowed for the valve cannot be easily adjusted to allow for a larger valve assembly to be connected between the flanges of the piping system. Each required valve will need to be provided with its own standardized space or length for attaching such valve to the piping system mainly to facilitate future replacement of the valve with a valve from any manufacturer.
In some current piping systems, where a check valve and a separate closure or block valve are needed in the piping system, two standardized valve spaces would be required in the piping system to accommodate the two valves.
In another example, for a double block and bleed operation, two valves are provided that each have an sealing means for creating a barrier to fluid flow in both directions along a pipe of the piping system. Between the two valves of the double block and bleed assembly is a void space that can be vented to confirm that the dual seals are being maintained as required by, for example, the Occupational Safety and Health Administration and by other international safety organizations and practices. Therefore for traditional double block and bleed assemblies, at least two standardized valve spaces would be required in the piping system to accommodate the two valves.